The following includes information that may be useful in understanding the present inventions. It is not an admission that any of the information provided herein is prior art, or relevant, to the presently described or claimed inventions, or that any publication or document that is specifically or implicitly referenced is prior art.
Orthotic devices generally include a substantially rigid biomechanical element that forms the basis of the skeletal support that is required for the majority of these devices, which include braces, supports and splints.
The human knee generally comprises an articulated joint between the thigh and the lower leg muscles that supports the weight of the human body while the person is standing, walking or running. The knee joint is primarily held together by four ligaments; namely, the anterior and posterior cruciate ligaments and the medial and lateral collateral ligaments. The knee joint can be overly weakened by injuries arising out of cartilage damage and ligament strain, which may be caused, by sports injuries, as well as from everyday exercising, or physiological problems such as osteoarthritis. Thus, the human knee is subjected to a variety of stresses and strains particularly during running and jumping movements. Athletes, in particular, are apt to incur a knee injury as a result of a blow to the knee or to a twisting of the knee, which can commonly occur in various contact sports or high stress sports, such as skiing. Normal aging of the knee joint results in diminished knee stability. Muscle control may be reduced; ligaments become lax and thus less effective.
There are a variety of knee braces available on the market or through healthcare providers. These range from braces that tend to totally immobilize the knee to flexible elastic bandages that are intended to provide some flexibility while eliminating lateral movement of the ligaments that support the knee. Some of these are braces intended to be worn as a relatively permanent device for long-term wear or braces that are intended to be worn for a short period of time during overly strenuous for a short period of time, for example, for a weakened knee. The braces have as their primary object to allow for bending and straightening the knee while preventing any unnatural movement, which may aggravate the knee ligaments. While the braces are intended to allow for a natural movement of the knee joint while a person undergoes walking, running, jumping, skating, various other athletic activities, they are intended also to prevent sudden movement of the upper and lower legs to one side or the other and to prevent twisting or rotation of the lower leg relative to the upper leg about the vertical axis.
Typically, the knee braces are held in place by flexible straps, which wrap about the user's thigh and calf above and below the knee, respectively. In this manner, the rigid hinge of the knee brace remains positioned on either side of the user's knee so as to mimic the hinged joint of the knee. However, it is not uncommon for the user's bodily motions to cause the flexible straps to move relative to the person's leg, thereby misaligning the knee brace with respect to the knee. This movement of the brace straps with respect to the user not only cause misalignment and therefore misapplication of the orthotic device, but also cause irritation of the user's skin by this unintended rubbing.
Another problem with knee braces is that they must engage effectively with soft tissue in order to provide the desired support. In many parts of the body the soft tissue will move, for example by expanding or contracting as result of muscle movement. This can cause distal migration of the knee brace with respect to the users leg, which means that the brace is not providing its desired support function. As a soft tissue changes shape, parts of the skin lose contact with the liner of the brace. This reduced contact with the liner can cause the knee brace to lose position, or move relative to the user and therefore become ineffective. The only way of overcoming this problem with existing devices is to tighten the device. This causes discomfort, prevents the skin from breathing, and can irritate the skin about the edges of the device and the liner.
The objective of any rigid knee brace is to exert a predictable force on the user's underlying skeleton. In particular, the objective is to exert a force on the tibia with respect to the femur in the user's body mass above the knee. By definition, knee braces are applied to soft tissue lying between the brace and the user's skeleton. Soft tissue is mobile and moves in a cycle corresponding to a user's gait, whether it be through running, walking or other physical movement common to the human knee. The most mobile soft tissue is the quadriceps mechanism lying in front of the femur in the anterior thigh region.
The central reference point for a knee brace is the knee joint line. In construction, a knee brace would use a rigid joint mechanism that mimics the movement of the knee, which is not just a simple hinge. Because each user's body shape is unique, the exact interface between the knee brace and the user's leg cannot be predetermined in the manufacture of such a device.
The function of the tibial section attached to this joint or central axis is to “fit and grip” the tibia and exert a force on it. In ligament instability bracing is intended to prevent anterior translocation of the tibia with respect to the femur. It is also desired to prevent the tibia deforming into varus (bow legged) or valgus (knock kneed). This is important because often injuries to the collateral ligaments coexist with cruciate ligament related pathology, and resulting instability. In bracing for osteoarthritis the objective is to exert an unloading force on the side of the knee joint most affected by degenerative pathology. This is achieved by “pushing” the tibia into a slight valgus deformity, or less frequently, a slight varus deformity.
The function of the femoral, or thigh portion is to stabilize the central axis, or knee joint, and to provide a lever arm or counteracting force for the tibial section. Ideally the central axis, and attached tibial section, remain in a stable position relative to the actual underlying knee joint. Ideally the “lever arms” extending up the thigh remain in a stable position aligned with the underlying femur.
An improved knee brace is described in applicant's co-pending application entitled “Knee Brace”, filed on even date herewith, which application is hereby incorporated by reference herein in its entirety.
Applicant's co-pending application describes a knee brace which can more readily conform to a particular user's leg, such that the straps fit snugly, yet comfortably, about the user's leg adjacent the knee, but yet provide the adequate support so as to prevent relative movement of the knee brace with respect to the knee so that the brace provides its desired function. It would be advantageous to provide a knee brace having, for example, a larger thigh engagement structure.